By the time the Endangered Species Act was passed in 1973 Southern California’s picturesque Channel Islands had already devolved into an environmental nightmare. Overrun by introduced species, the islands’ delicate and highly unique web of life was unraveling toward the point of no return.

Forty years later, the eight-island archipelago stands as testament to the fact that man-made problems have solutions if we’re willing to do the work.

The recent announcement that the island night lizard – protected under the Endangered Species Act since 1977 – has met recovery goals and no longer needs federal protection is the culmination of a three-decade effort to reverse a century of habitat and rare species destruction on the islands.

The extraordinary recovery of the slow-growing four-inch lizards is also the latest proof that the Endangered Species Act, which marks its 40thanniversary this year, works quite effectively when we fully commit to protecting not only imperiled plants and animals, but the places they live.

Once rare, the lizards now number more than 21 million on one island and more than 15,000 on two others. The rebound came only after federal protections that resulted in disciplined habitat protection and the removal of nonnative species. Those efforts have also led to the gradual recovery of several of the islands’ imperiled plants, including two that were deemed recovered just last year, as well as encouraging rebounds in populations of the cat-sized island fox and the San Clemente loggerhead shrike.

Long considered one of the world’s most endangered songbirds, shrike populations had shrunk to fewer than 20 individuals before federal protection. At last count, there were roughly 185 birds. The island fox, which once numbered in the thousands, had been reduced into the teens on two islands, and fewer than 60 on another. But with the help of the Endangered Species Act, its numbers have now swelled to more than 1,000.

The Channel Islands, which stretch for 160 miles from Santa Barbara to San Diego, are an intriguing chapter in the natural history of California. Their small size and proximity to the coast led to multiple events of species colonizing the islands from the mainland and then evolving into new species – like the island night lizard – that adapted to the island’s sun-drenched days and chilly nights.

But in the late 1800s, cattle, sheep, goats, rabbits, and pigs were introduced to the islands, leading to a downward cascade of dozens of plants and animals and an overall unraveling of the islands’ ecosystems. In one particularly interesting yet troubling example of this unraveling, the use of DDT in the 1960s led to the extirpation of the bald eagle on the islands. At the same time, the introduction of pigs provided a source of prey for golden eagles which, in the absence of bald eagles, colonized and subsequently began preying on island foxes, leading to their near extinction.

Efforts to remove introduced animals from the islands began in the 1960s, but really took off in the 1980s following protection of many species under the Endangered Species Act, including the island night lizard. Cooperative efforts by the U.S. Fish and Wildlife Service, National Park Service, and U.S. Navy, which has a large presence on the islands, led to the eradication of many nonnative animals, including rabbits on Santa Barbara Island and goats on San Clemente Island, which in both cases have directly contributed to the recovery of the island night lizard.

None of this would have happened without the framework for recovery provided by the Endangered Species Act. Over the past four decades, the Act has repeatedly demonstrated that, when used to the full extent of the law, it works. To date, more than 99 percent of the more than 1,400 plants and animals under its care have been saved from extinction. And a study last year of more than 100 of those species found the great majority to be meeting or exceeding recovery timelines set by federal scientists.

But it’s instructive to remember that for some Channel Island species, federal protections came far too late. Several plants and animals native to the islands have already gone extinct, including the Santa Cruz Island monkeyflower and the Santa Barbara Island song sparrow.

As we take on the complex environmental challenges of the 21st century, those lost species serve as a constant reminder that the single greatest limitation on the Endangered Species Act’s ability to help us recover our scarred planet is our willingness to use it.